waitcnt — LLVM 22.1.3 documentation

# waitcnt

Counts of outstanding instructions to wait for.

The bits of this operand have the following meaning:

> Bits | Description | Value Range
> --- | --- | ---
> 2:0 | EXP_CNT: export and LDSDIR count. | 0..7
> 3:3 | Unused | -
> 9:4 | LGKM_CNT: LDS, GDS, Constant and Message count. | 0..63
> 15:10 | VM_CNT: vector memory operations count. | 0..63

This operand may be specified as one of the following:

- An integer_number or an absolute_expression. The value must be in the range 0..0xFFFF.

- A combination of vmcnt, expcnt, lgkmcnt and other values described below.

  > Syntax | Description
  > --- | ---
  > vmcnt(<N>) | A VM_CNT value. N must not exceed the largest VM_CNT value.
  > expcnt(<N>) | An EXP_CNT value. N must not exceed the largest EXP_CNT value.
  > lgkmcnt(<N>) | An LGKM_CNT value. N must not exceed the largest LGKM_CNT value.
  > vmcnt_sat(<N>) | A VM_CNT value computed as min(N, the largest VM_CNT value).
  > expcnt_sat(<N>) | An EXP_CNT value computed as min(N, the largest EXP_CNT value).
  > lgkmcnt_sat(<N>) | An LGKM_CNT value computed as min(N, the largest LGKM_CNT value).

These values may be specified in any order. Spaces, ampersands and commas may be used as optional separators.

N is either an integer number or an absolute expression.

Examples:

    s_waitcnt vmcnt(1)
    s_waitcnt expcnt(2) lgkmcnt(3)
    s_waitcnt vmcnt(1), expcnt(2), lgkmcnt(3)
    s_waitcnt vmcnt(1) & lgkmcnt_sat(100) & expcnt(2)